A pathological diagnosis provides information important for determination of a treatment strategy. In a case where a pathological diagnosis is made, it is considered preferable to employ a double check system in order to avoid occurrence of a wrong diagnosis. This double check system is a system in which (i) a pathologist A makes a diagnosis, (ii) a pathologist B also makes a diagnosis, and then (iii) an outcome of a pathological diagnosis is determined based on findings which the respective pathologists A and B have obtained. However, under the circumstances, the absolute number of pathologists who make pathological diagnoses is insufficient, except for some of the developed countries. Moreover, such pathologists mostly work in hospitals in metropolitan areas and the like, and many hospitals do not have full-time pathologists. Therefore, not only in Japan but also in the world, it is not easy to always have a plurality of pathologists and let them promptly make pathological diagnoses. Furthermore, it is said that, in Japan, the average number of tissue slides which a pathologist observes so as to make pathological diagnoses is approximately 10,000 per year. As such, each pathologist has a heavy work load. In view of the circumstances, development of a technique has been desired which assists a pathologist in making a pathological diagnosis by causing a computer to take on a role of the pathologist in making the pathological diagnosis.
In a case where a pathologist makes a pathological diagnosis, the pathologist is required to make an objective determination on the basis of a morphological finding with regard to a tissue and/or cells which morphological finding is obtained by microscopic observation. However, some lesions are difficult to correctly classify and distinguish on the basis of merely morphological findings. Therefore, there is a possibility that a wrong pathological diagnosis, such an overlook of a lesion, is made. Furthermore, in a case where a pathologist makes a pathological diagnosis on the basis of subjective determination based on his/her experience, an outcome of the pathological diagnosis may vary depending on the pathologist. This causes a reduction in reliability of the pathological diagnosis. The technique which assists a pathologist in making a pathological diagnosis is required not to cause a wrong diagnosis, and is required to provide an objective criterion for a diagnosis.
In order that an image of, for example, a tissue slide used for a pathological diagnosis is analyzed with use of a computer, introduction of a topological idea has been suggested. As an example of the technique which assists a pathologist in making a pathological diagnosis, Patent Literature 1 discloses an image analyzing device which extracts a cancer lesion with reference to a pathological image. The image analyzing device disclosed in Patent Literature 1 calculates, for each region, homology per unit area of the pathological image, and then determines whether or not the each region is a target region (for example, a region including the cancer lesion).
Non-Patent Literature 1 discloses a method of analyzing an image of a liver under a concept of persistent homology and classifying a lesion in the liver.